Overseas sex tours and the ongoing Euro 2012 football championship have made cracking down on prostitution and gambling increasingly difficult,said Ho Chi Minh City police at a conference on Tuesday.

The police said a trend has emerged in which Vietnamese prostitutes travel abroad to provide the service, news website VietNamNet reported.

Early this month, HCMC police busted a major sex ring run by beauty queens and models Vo Thi My Xuan from the Mekong Delta and Thien Kim from the city, which paired Vietnamese prostitutes and clients for three-day sex tours to Singapore at a cost of US$25,000.

The ring has exposed the city's sex industry as "sophisticated" and "complicated," according to a police statement at the conference.

It said prostitutes have both gone abroad looking for customers and brought wealthy Vietnamese men with them.

So far this year, the city police have busted 43 prostitution operations, sending 46 prostitutes to rehabilitation and counseling centers.

The gambling situation is complex as well, said the police who have seized more than VND2.6 billion ($124,550) and nearly $3,500 in cash from 857 raids.

The police said more gambling activity is being conducted via phone calls and online which are difficult to trace and have made it tough for police to gather evidence or catch perpetrators red-handed.

They said they would work hard to control football gambling during the Euro 2012.

In related news, police at the conference said they have seized nearly 20 kilograms of heroin in different forms this year and that cases of drug trafficking are down five percent from the same period last year.